title: Populus euphratica XTH overexpression enhances salinity tolerance by the development of leaf succulence in transgenic tobacco plants.
abstract: Populus euphratica is a salt-tolerant tree species that develops leaf succulence after a prolonged period of salinity stress. In the present study, a putative xyloglucan endotransglucosylase/hydrolase gene (PeXTH) from P. euphratica was isolated and transferred to tobacco plants. PeXTH localized exclusively to the endoplasmic reticulum and cell wall. Plants overexpressing PeXTH were more salt tolerant than wild-type tobacco with respect to root and leaf growth, and survival. The increased capacity for salt tolerance was due mainly to the anatomical and physiological alterations caused by PeXTH overexpression. Compared with the wild type, PeXTH-transgenic plants contained 36% higher water content per unit area and 39% higher ratio of fresh weight to dry weight, a hallmark of leaf succulence. However, the increased water storage in the leaves in PeXTH-transgenic plants was not accompanied by greater leaf thickness but was due to highly packed palisade parenchyma cells and fewer intercellular air spaces between mesophyll cells. In addition to the salt dilution effect in response to NaCl, these anatomical changes increased leaf water-retaining capacity, which lowered the increase of salt concentration in the succulent tissues and mesophyll cells. Moreover, the increased number of mesophyll cells reduced the intercellular air space, which improved carbon economy and resulted in a 47-78% greater net photosynthesis under control and salt treatments (100-150 mM NaCl). Taken together, the results indicate that PeXTH overexpression enhanced salt tolerance by the development of succulent leaves in tobacco plants without swelling.
authors.affiliation: College of Biological Sciences and Technology (Box 162), Beijing Forestry University, Beijing 100083, China.
authors.forename: Yansha
authors.initials: Y
authors.lastname: Han
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Jian
authors.initials: J
authors.lastname: Sun
authors.forename: Mingquan
authors.initials: M
authors.lastname: Ding
authors.forename: Rui
authors.initials: R
authors.lastname: Zhao
authors.forename: Shurong
authors.initials: S
authors.lastname: Deng
authors.forename: Feifei
authors.initials: F
authors.lastname: Wang
authors.forename: Yue
authors.initials: Y
authors.lastname: Hu
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Lu
authors.forename: Liping
authors.initials: L
authors.lastname: Du
authors.forename: Zanmin
authors.initials: Z
authors.lastname: Hu
authors.forename: Heike
authors.initials: H
authors.lastname: Diekmann
authors.forename: Xin
authors.initials: X
authors.lastname: Shen
authors.forename: Andrea
authors.initials: A
authors.lastname: Polle
authors.forename: Shaoliang
authors.initials: S
authors.lastname: Chen
mesh_terms: D002712:Chlorides / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D005453:Fluorescence; D017343:Genes, Plant; D058503:Mesophyll Cells / Q000166:cytology / Q000378:metabolism; D019697:Onions / Q000166:cytology; D010788:Photosynthesis; D019441:Plant Epidermis / Q000166:cytology; D018515:Plant Leaves / Q000033:anatomy & histology / Q000254:growth & development / Q000502:physiology*; D010940:Plant Proteins / Q000378:metabolism*; D018517:Plant Roots / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D032107:Populus / Q000235:genetics* / Q000502:physiology*; D021381:Protein Transport; D055049:Salt Tolerance / Q000502:physiology*; D012964:Sodium / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics*; D014170:Transformation, Genetic; D014867:Water / Q000378:metabolism
chemical_list: D002712:Chlorides; D010940:Plant Proteins; D014867:Water; D002734:Chlorophyll; D012964:Sodium; D000077194:Chlorophyll A
keywords: Chlorophyll a fluorescence; NaCl; Populus euphratica; leaf anatomy; photosynthesis; root length; salt compartmentation; water-retaining capacity; xyloglucan endotransglucosylase/hydrolase gene.